Amino acid hydroxylases are enzymes useful for production of intermediates of pharmaceuticals and the like, and the presence of proline 4-hydroxylase (Non-patent Document 1), L-isoleucine dioxygenase (Non-patent Document 2), and the like has been reported. In terms of enzymes having an ability to hydroxylate pipecolic acid, several kinds of proline hydroxylases have been reported to have an ability to hydroxylate 3-position or 5-position of L-pipecolic acid (Non-patent Document 3). However, no enzyme has so far been reported to hydroxylate 4-position of pipecolic acid.
The amino acid sequences of SEQ ID NOs: 2, 4, 6, 8, 10, and 12 are the same as GenBank accession NOs. EGU81245, XP_001827566, XP_002558179, XP_383389, ELA34460, and XP_659994, respectively, which are the amino acid sequences translated from the putative protein-coding DNA sequences based on genomic sequence information of the Fusarium oxysporum Fo5176 strain, Aspergillus oryzae RIB40 strain, Penicillium chrysogenum Wisconsin 54-1255 strain, Gibberella zeae (another name, Fusarium graminearum) PH-1 strain, Colletotrichum gloeosporioides Nara gc5 strain, and Aspergillus nidulans (another name, Emericella nidulans) FGSC A4, respectively. Since all of these proteins are derived from fungi, the proteins, if exist, are likely to be in a state where they have undergone glycosylation after their expression. However, there has been no report supporting their existence based on actual isolation or the like, and the functions of these proteins have been unknown at all.
Optically active 4-hydroxy amino acids are useful substances as intermediates of pharmaceuticals and the like. For example, (4S)-hydroxy-L-pipecolic acid can be used as a precursor of a Rho kinase inhibitor (Patent Document 1), and (4S)-hydroxy-D-pipecolic acid can be used as a precursor of CGS-20281, which is an NMDA receptor inhibitor (Non-patent Document 4). (4R)-Hydroxy-L-proline can be used as a precursor of icatibant acetate, which is a bradykinin B2 receptor inhibitor (Non-patent Document 5), and (4R)-hydroxy-D-proline can be used as a precursor of a factor Xa inhibitor (Patent Document 2). L-Homoserine can be used as a precursor of Omapatrilat, which is an ACE inhibitor (Patent Document 3), and 4-hydroxy-L-leucine can be used as a precursor of SCY-635, which is a cyclophilin inhibitor (Non-patent Document 6).
Examples of previously reported methods for synthesis of an optically active 4-hydroxy amino acid include a method in which (4S)-hydroxy-L-pipecolic acid or (4S)-hydroxy-D-pipecolic acid is produced by stereoselective cyclization of 3-butenol with an optically active C-aminocarbonyl nitrone or C-alkoxycarbonyl nitrone has been reported so far (Non-patent Document 7). A method in which (4R)-hydroxy-L-proline is synthesized from L-proline using proline 4-hydroxylase derived from the Dactylosporagium RH 1 strain (Non-patent Document 1), and a method in which (4R)-hydroxy-D-proline is synthesized via an α,β-didehydroamino acid (Non-patent Document 8) have also been reported. A method in which L-homoserine is synthesized by fermentation using a recombinant E. coli (Patent Document 4), and a method in which 4-hydroxy-L-leucine is synthesized from L-leucine using L-isoleucine dioxygenase derived from the Bacillus thuringiensis 2e2 strain (Non-patent Document 2) have also been reported.
However, more efficient synthesis methods have been demanded since these methods have problems such as expensive materials, large numbers of steps, small numbers of the types of compounds to which the methods are applicable, and high purification loads.